Switching apparatuses for electrical switching devices and such electrical switching devices are known in principle. In order to be able to activate and deactivate a power circuit, such switching apparatuses frequently have a rotatable rotor housing, which can be rotated between an open position and a closed position. In the closed position contacts are connected to one another in an electrically conducting manner, while in the open position said contacts are isolated electrically from one another.
Also provided with known switching apparatuses is a switching unit, which can be moved by way of a switching lever at least between an ON position and an OFF position. A lever mechanism is frequently provided between the switching unit and the rotatable rotor housing, converting the movement between the ON position and the OFF position to a movement between the closed position and the open position of the rotor housing. In other words the switching lever can be used to activate and deactivate the switching apparatus. Known switching apparatuses are used for example to activate and deactivate or monitor electrical networks. Such switching apparatuses are therefore frequently provided with trip mechanisms, which isolate the power circuit in the event of a short circuit or current increases for some other reason, in other words they rotate the rotor housing into the open position.
It can happen with known switching apparatuses that a failure results in the interior of the switching apparatus due to very large short circuit currents. When the contacts are isolated therefore arcing can occur, causing the contacts to become welded together due to its high temperatures. In other words a moving contact is not released from a fixed contact at this point, even though the switching lever moves from the ON position.
With known switching apparatuses after tripping, also referred to as a TRIP situation, the functionality of the trip mechanism must be restored. With known switching apparatuses the switching lever is moved by way of a RESET position into the OFF position for this purpose. In this process for example a spring element is tensioned, so that during subsequent operation a new tripping operation can take place by way of the force stored in the spring element. If however after tripping the fixed contacts are welded to the moving contacts, there is a risk that the decoupling of the switching lever or switching unit from the rotor housing will still cause movement of the switching lever into the OFF position or by way of the RESET position into the OFF position.
Despite the switching lever being positioned in the OFF position, in other words giving the appearance that the switching apparatus is disconnected from the power, the welding of the moving contact to the fixed contact here would mean that the power circuit of the switching apparatus is closed. In such an instance therefore the switching apparatus provides incorrect information, so there is a risk of a user of an inventive switching apparatus suffering an electric shock from a machine due to the misinformation from the OFF position of the switching lever. Such positioning of the switching lever in the OFF position when the switching circuit is activated due to the closed position of the rotor housing is also referred to as a positive off. This situation carries a major risk, as the switching lever in the OFF position suggests protection that is not there, in other words a currentless power circuit.